Methods exist for the analysis of functional fluids, including lubricating oils. In particular, methods and apparatus for testing the condition or identity of a fluid include chromatography and chemical analysis. These methods generally require controlled conditions and specialized training.
Other methods and apparatus for assessing the quality of a used fluid include placing a measured amount of fluid upon an absorbent material, heating the sample and awaiting dispersion of the sample. The amount of undispersed sample may then be measured and rated quantitatively. These methods and apparatus require significant controlled conditions, including measurement of the fluid sample volume, the use of a template to measure and rate the quantity of undispersed the sample. Additionally these methods can include heating of the sample, and awaiting dispersal of the sample. Another method to analyze oil is disclosed in U.S. Pat. No. 5,313,824; to Hergruth, et al. comprising the steps of obtaining a sample of the oil, placing the sample upon the medium, maintaining the medium in a desired position for an effective period of time for the spot to be visible, visually comparing the spotted test medium against comparative visual indicia depicting lubricating oil in various conditions, and selecting the comparative example which most closely resembles the test medium spotted with the test sample. No chemical reaction to occurs between the medium and the fluid, and it is just a visual observation of what the oil looks like compared to a standard.
Markers have been used to identify fluids. Proton accepting chemical substances, that at a solution concentration of below about 50 milligrams per liter, impart little or no significant color to organic solvents, have been proposed as markers, or taggants, especially for petroleum-derived fuels. The marker is dissolved in a liquid to be identified, and then subsequently detected by performing a chemical test on the marked liquid. Markers are sometimes employed by government agencies to ensure that the appropriate tax has been paid on particular grades of fuel. Oil companies also mark their products to help assist in identifying diluted or altered products. These companies often go to great expense to make sure their branded petroleum products meet certain specifications, for example, volatility and octane number, as well as to provide their petroleum products with effective additive packages containing detergents and other components. Consumers rely upon product names and quality designations to assure that the product being purchased is the quality desired. Thus, it is important to be able to identify a marker in a petroleum product.
Traditionally, the presence of a marker substance is detected and optionally quantified by extracting the fuel with an immiscible aqueous or significantly aqueous solution of an acid substance, the precise nature of which can be varied according to the characteristics of the marker substance. The acid reacts with the basic compound to produce a readily visible, more or less intensely colored cation, that is dissolved in the aqueous acid phase. This method is disclosed in U.S. Pat. No. 5,145,573. Additionally, a method has been disclosed in WO 03/078551 A2 where the acidic substance has been applied to a test strip. The test strip is dipped into the oil and diazo-type marker reacts with the acidic substance in the test strip and changes color.
The quantity of marker substance in the extract may also be measured, for instance, by visible light absorption spectrophotometry, the results of which are then compared with a reference standard to determine the original concentration of basic marker in the fluid. It may be necessary to make repeated, typically two or three, extractions of the fluid to recover the entire amount of marker originally present in order for complete quantification. Additionally, the extracted, separated phase is classifiable as a hazardous waste and presents problems of safe and lawful disposal, especially when examinations are made “in the field.” Furthermore, the fluid with which was tested may be contaminated, making return to its original source undesirable and presenting additional waste disposal problems.
A need exists for a simple and rapid method of chemically analyzing a sample of a fluid on a qualitative basis to determine condition, origin or other useful property. The present invention will rapidly indicate the condition of a functional fluid such as lubricating oils, engine oil, transmission fluids, greases, gear oils, hydraulic fluids, metalworking fluids, antifreeze fluids, coating system fluids, cooling systems fluids, farm tractor fluids, transformer fluids, fuels such as diesel, gasoline, biofuels, emulsified fuels, and the like in the field. Many owners/operators of equipment that depend on these functional fluids currently depend on standard guidelines, such as hours or mileage, to determine the appropriate interval to change the functional fluid (end of useful life). Additionally, labs are relied on today to determine the specific identify of a fluid, where a tool that would allow identification in the field would speed warranty resolution. Finally, since various absorbent materials (wipes, shop towels, paper towels, and napkins) are normally used in checking these functional fluids, it is conceived that the present invention combines the necessary utility of these absorbent materials with a diagnostic functionality that provides additional benefit.